Abrasive paper or cloth



Patented Sept. 11, 1928.

UNITED STATES PATENT OFFICE.

RALPH B. MANLIEY, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE CARBORUNDUM COMPANY, OF NIAGARA FALLS, NEW YORK, A CORPORATION OF PENNSYLVAN IA.

ABRASIVE PAPER R CLOTH.

No Drawing.

' This invention relates to an improved article of abrasive paper or cloth in which artificial aluminous abrasive grains are coated on the paper or cloth in a manner which accomplishes new and valuable results in certain lines of work. Artificial aluminous abrasive, otherwise known as artificial corundum, aloxite, alundum, etc., is a form of crystalline fused alumina made by fusing l0 bauxite in the electric furnace and containing about 90% and upwards of alumina. It is widely used in the manufacture of abrasive paper and cloth, which is of special utility in the grinding and polishing of 5 metals and has largely displaced emery cloth for this particular purpose. The present invention relates to the adaptation of this type of abrasive paper or cloth for the cutting and polishing of wood and for general use in Woodworking trades.

The type of abrasive paper and Cloth which has heretofore been found most ellicient in the woodworking trades is that in which the natural mineral garnet is used as the abrasive. Garnet seems to break up into gra'ns which have fractures or cutting edges n'iaking them especially efficientin cutting wood. Garnet has a hardness of 7 to 7.5 and artificial aluminous abrasive a hardness u of over 9. Notwithstanding the fact that artificial aluminous abrasive is greatly superior to garnet in hardness and has a sharpness and fracture which compares favorably with it, it has never been successfully used in the 5 woodworking trades because the paper or cloth does not cut freely but fills up rapidly and after a short time the cutting action is very much reduced. Various expedients have been tried to overcome this but 0 without success. I have now discovered certain variations in the methods of coating these grains on the paper which produce a material having greateffici ency and durability for the cutting of wood. Aluminous 5 abrasive paper or cloth as ordinarily produced is made by running the paper or cloth through a coating machine which first coats the paper or cloth with a film of liquid glue, following which the abrasive grains are 0 sprinkled on the coated glue surface in a uniform stream and there is thus produced a regular uniform coating. "This coating covers practically the full surface of the paper Or cloth and. leaves very few or no mter- Application filed. August 18, 1924. .Serial No. 732,878.

sti-ces which are uncovered. I have discovered that if the coatimg procedure is so controlled that the surface of the paper or cloth is only partially covered with grain uniformly sprinkled thereon and a considerable portion left uncovered in the form of blank spaces between the individual grams or small groups of grains, the cutting action of the paper or cloth on wood is profoundly modified and improved. Preferably, the grains cover from 25% to 75% of the total surface area of the paper or cloth backing. As will be readily apparent, when the grains are so sparsely sprinkled on the adhesive coated surface as to cover but 25% to 7 5% of its surface, the grains will not be superimposed on each other as in the usual full coated abrasive sheets, but will lie for the most part in a single thickness layer having small irregular shaped uncovered blank or open spaces between the grains. Since the grains are sprinkled on to the adhesive coated sheet, the individual grains will necessarily'fall and lie in a more or less haphazard or irregular formation, although the general density of distribution of the abrasive grains is substantially uniform over the area of the sheet. The small irregular uncovered open spaces will likewise be substantially uniformly distributed between the grains throughout the area of the abrasive sheet. By the expression between the grains is meant either between individual grains or between small irregular groups or clusters containing but a few grains. With a full coating of grain as formerly made, the small clearances between the projecting points of grain soon gathered enough wood particles so as to fill up the surface. This prevented penetration of the cutting points and stopped the paper or cloth from cutting long before the points were dulled or the paper or cloth worn out. Under my improved method, the open spaces which are left provide clearances for the ground material cut away from the wood. This ground material lodges temporarily in the open spaces and then falls away and allows full penetration of the cutting points. There is no filling up of the paper or cloth, and with this impediment removed it is found that aluminous abrasives far excel garnet in the cutting of wood.

The efliciency of my improved paper or cloth is especially noticeable in cutting and finishing hard woods, such as furniture of oak, lllzlllngun). etc. In many cases it has shown a durability of from 25% to 50% greater and at the same time it cuts faster. It may be used in the form of belts or as a covering on drum sanders, or in (11505, sheets or any of the shapes commonly used.

I claim:

1. A ne article of manufacture compris ing a backing coated with aluminous abrasive grains distributed substantially uniformly over the surface of the backing, all of the grains being substantially imlividually spaced with resiect to the other grains, whereby the surf ace of the backing is substantially free from grain clusters so as to leave uncovered portions of the backing sufticient in size to prevent the permanent lodgment therein, of material which has been ground away.

2. As a new article of manufacture, a flexible backing coated with isolated grains of artificial aluminons abrasive, individually spaced over the surface of the backing so as to leave uncovered spaces between the grains constituting from 25" to 75% of the total surface area of the backing.

3. As a new article of manufacture, a flexible abrasive sheet comprising a flexible backing covered with a substantially continuous coating of adhesive and having grains of artificial aluminous abrasive so sprinkled on the adhesive-coated surface that the grains will lie haphazardly but with a sub stant'ially uniform density of distribution over the area of the sheet, and applied so sparsely as to leave suflicient small irregular shaped uncovered spaces between the grains to provide effective clearances for the temporary lodgmcnt and discharge of the material ground otf by the abrasive.

In testimony whereof I have hereunto set my hand.

RALPH B. MANLEY. 

